The biggest point of interest with duergar would be psionics.
The invisibility and enlarge person abilities of duergar in Eberron are considered psionic abilities. Kieth Baker himself described Eberron duergar as "twisted deep dwarves" from ruined holds. Sarlona was entry point for the quori. The sheer number on this continent impacted the natives resulting in the continent of Sarlona producing the majority of inherent psionics. The duergar were also hired and betrayed/enslaved by the Inspired. The close proximity to psionic beings on the continent where they, the psionic beings, emerged in the largest number is what gave the duergar psionic abilities.
By contrast, in Forgotten Realms the invisibility and enlarge person are considered spell-like abilities instead of psionics, though they do stem from Illithids. In FR, illithids used surgery and eugenics to breed the duergar into being better overseers over other slaves of the illithids. The duergar would rebel against the illithids and, their eventual demigoddess Deep Dura, had surgeries performed on many captured illithids to learn the secrets of psionics, the "invisible arts", from the illithids and embedded it racially into the duergar. So even though they were psionic originally in lore, the racial embedding by the duergar demigod is largely why in FR the abilities are considered racial spell-like abilities instead of true psionics.
I bring psionics up because I think I vaguely remember many years ago devs saying that psionics would not be a part of ddo. It will be interesting to see if the anti-psionic stance has changed given that the duergar of Eberron are inherently psionic in nature and the ones of FR were heavily influenced by psionics.
